Air precleaners are used for removing particulates from the air prior to moving the air through an air cleaner connected to a carburetor or air intake structure of an internal combustion engine. Petersen in U.S. Pat. No. 3,670,480 discloses an air precleaner having a rotatable impeller or spinner operable to separate particles from air, discharge air and particles circumferentially from a housing, and direct clean air to the air intake structure of an engine. The clean air moves centrally through a stack to an engine in response to a vacuum pressure on the air moving to the engine. This precleaner has an air inlet vane assembly located in the bottom of the housing for directing air upwardly in a circular path into a centrifugal separation chamber. The air flows upwardly and then turns downwardly into the centrally located clean air exit opening. The impeller is used to pump air and particulate matter out through side discharge openings. While this device is operative, it does not take full advantage of the power of the vortex-like air flow in the mouth region of the clean air outlet passage.
Air cleaning devices having propeller blades located in air flow passages for turning a rotor having vanes have been proposed to separate dirt from air. Examples of this type of device are disclosed by Quam in U.S. Pat. No. 1,434,562 and No. 1,438,553 in U.S. Pat. No. 1,530,825. The vanes move the incoming air in a circumferential direction to a separating chamber where the dirt particles are subjected to centrifugal force which moves them outwardly. The outside strata of air and dirt is pumped by the moving vanes out of the bottom of the separation chamber. The vanes must be in the separation chamber to provide the necessary circumferential motion to the air.